/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.juneau.bean.openapi3;

import static org.apache.juneau.commons.utils.AssertionUtils.*;
import static org.apache.juneau.commons.utils.CollectionUtils.*;
import static org.apache.juneau.commons.utils.Utils.*;
import static org.apache.juneau.internal.ConverterUtils.*;

import java.util.*;

import org.apache.juneau.annotation.*;
import org.apache.juneau.commons.collections.*;

/**
 * Describes a single HTTP header.
 *
 * <p>
 * The Header Object follows the structure of the Parameter Object with the following changes: it does not have a
 * <c>name</c> field since the header name is specified in the key, and it does not have a <c>required</c> field
 * since headers are always optional in HTTP.
 *
 * <h5 class='section'>OpenAPI Specification:</h5>
 * <p>
 * The Header Object is composed of the following fields:
 * <ul class='spaced-list'>
 *    <li><c>description</c> (string) - A brief description of the header (CommonMark syntax may be used)
 *    <li><c>required</c> (boolean) - Determines whether this header is mandatory (default is <jk>false</jk>)
 *    <li><c>deprecated</c> (boolean) - Specifies that a header is deprecated
 *    <li><c>allowEmptyValue</c> (boolean) - Sets the ability to pass empty-valued headers
 *    <li><c>style</c> (string) - Describes how the header value will be serialized
 *    <li><c>explode</c> (boolean) - When true, header values of type array or object generate separate headers for each value
 *    <li><c>allowReserved</c> (boolean) - Determines whether the header value should allow reserved characters
 *    <li><c>schema</c> ({@link SchemaInfo}) - The schema defining the type used for the header
 *    <li><c>example</c> (any) - Example of the header's potential value
 *    <li><c>examples</c> (map of {@link Example}) - Examples of the header's potential value
 * </ul>
 *
 * <h5 class='section'>Example:</h5>
 * <p class='bcode'>
 *    <jc>// Construct using SwaggerBuilder.</jc>
 *    HeaderInfo <jv>x</jv> = <jsm>headerInfo</jsm>(<js>"integer"</js>).description(<js>"The number of allowed requests in the current period"</js>);
 *
 *    <jc>// Serialize using JsonSerializer.</jc>
 *    String <jv>json</jv> = Json.<jsm>from</jsm>(<jv>x</jv>);
 *
 *    <jc>// Or just use toString() which does the same as above.</jc>
 *    String <jv>json</jv> = <jv>x</jv>.toString();
 * </p>
 * <p class='bcode'>
 *    <jc>// Output</jc>
 *    {
 *       <js>"description"</js>: <js>"The number of allowed requests in the current period"</js>,
 *       <js>"type"</js>: <js>"integer"</js>
 *    }
 * </p>
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://spec.openapis.org/oas/v3.0.0#header-object">OpenAPI Specification &gt; Header Object</a>
 *    <li class='link'><a class="doclink" href="https://swagger.io/docs/specification/describing-parameters/">OpenAPI Describing Parameters</a>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauBeanOpenApi3">juneau-bean-openapi-v3</a>
 * </ul>
 */
public class HeaderInfo extends OpenApiElement {

   private String description, ref;
   private Boolean required, explode, deprecated, allowEmptyValue, allowReserved;
   private SchemaInfo schema;
   private Object example;
   private Map<String,Example> examples = map();

   /**
    * Default constructor.
    */
   public HeaderInfo() {}

   /**
    * Copy constructor.
    *
    * @param copyFrom The object to copy.
    */
   public HeaderInfo(HeaderInfo copyFrom) {
      super(copyFrom);

      this.description = copyFrom.description;
      this.example = copyFrom.example;
      this.allowEmptyValue = copyFrom.allowEmptyValue;
      this.schema = copyFrom.schema;
      this.allowReserved = copyFrom.allowReserved;
      this.required = copyFrom.required;
      this.ref = copyFrom.ref;
      this.explode = copyFrom.explode;
      this.deprecated = copyFrom.deprecated;
      if (nn(copyFrom.examples))
         examples.putAll(copyOf(copyFrom.examples, Example::copy));
   }

   /**
    * Adds a single value to the <property>examples</property> property.
    *
    * @param name The example name.  Must not be <jk>null</jk>.
    * @param example The example.  Must not be <jk>null</jk>.
    * @return This object
    */
   public HeaderInfo addExample(String name, Example example) {
      assertArgNotNull("name", name);
      assertArgNotNull("example", example);
      examples.put(name, example);
      return this;
   }

   /**
    * Make a deep copy of this object.
    *
    * @return A deep copy of this object.
    */
   public HeaderInfo copy() {
      return new HeaderInfo(this);
   }

   @Override /* Overridden from OpenApiElement */
   public <T> T get(String property, Class<T> type) {
      assertArgNotNull("property", property);
      return switch (property) {
         case "description" -> toType(getDescription(), type);
         case "required" -> toType(getRequired(), type);
         case "explode" -> toType(getExplode(), type);
         case "deprecated" -> toType(getDeprecated(), type);
         case "allowEmptyValue" -> toType(getAllowEmptyValue(), type);
         case "allowReserved" -> toType(getAllowReserved(), type);
         case "$ref" -> toType(getRef(), type);
         case "schema" -> toType(getSchema(), type);
         case "x-example" -> toType(getExample(), type);
         case "examples" -> toType(getExamples(), type);
         default -> super.get(property, type);
      };
   }

   /**
    * Bean property getter:  <property>allowEmptyValue</property>.
    *
    * <p>
    * The type of the object.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public Boolean getAllowEmptyValue() { return allowEmptyValue; }

   /**
    * Bean property getter:  <property>allowReserved</property>.
    *
    * <p>
    * The type of the object.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public Boolean getAllowReserved() { return allowReserved; }

   /**
    * Bean property getter:  <property>deprecated</property>.
    *
    * <p>
    * The type of the object.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public Boolean getDeprecated() { return deprecated; }

   /**
    * Bean property getter:  <property>description</property>.
    *
    * <p>
    * A short description of the header.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public String getDescription() { return description; }

   /**
    * Bean property getter:  <property>x-example</property>.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   @Beanp("x-example")
   public Object getExample() { return example; }

   /**
    * Bean property getter:  <property>examples</property>.
    *
    * <p>
    * The list of possible responses as they are returned from executing this operation.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public Map<String,Example> getExamples() { return nullIfEmpty(examples); }

   /**
    * Bean property getter:  <property>required</property>.
    *
    * <p>
    * The type of the object.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public Boolean getExplode() { return explode; }

   /**
    * Bean property getter:  <property>$ref</property>.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   @Beanp("$ref")
   public String getRef() { return ref; }

   /**
    * Bean property getter:  <property>required</property>.
    *
    * <p>
    * The type of the object.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public Boolean getRequired() { return required; }

   /**
    * Bean property getter:  <property>schema</property>.
    *
    * @return The property value, or <jk>null</jk> if it is not set.
    */
   public SchemaInfo getSchema() { return schema; }

   @Override /* Overridden from SwaggerElement */
   public Set<String> keySet() {
      // @formatter:off
      var s = setb(String.class)
         .addIf(nn(ref), "$ref")
         .addIf(nn(allowEmptyValue), "allowEmptyValue")
         .addIf(nn(allowReserved), "allowReserved")
         .addIf(nn(deprecated), "deprecated")
         .addIf(nn(description), "description")
         .addIf(ne(examples), "examples")
         .addIf(nn(explode), "explode")
         .addIf(nn(required), "required")
         .addIf(nn(schema), "schema")
         .addIf(nn(example), "x-example")
         .build();
      // @formatter:on
      return new MultiSet<>(s, super.keySet());
   }

   /**
    * Resolves any <js>"$ref"</js> attributes in this element.
    *
    * @param openApi The swagger document containing the definitions.
    * @param refStack Keeps track of previously-visited references so that we don't cause recursive loops.
    * @param maxDepth
    *    The maximum depth to resolve references.
    *    <br>After that level is reached, <code>$ref</code> references will be left alone.
    *    <br>Useful if you have very complex models and you don't want your swagger page to be overly-complex.
    * @return
    *    This object with references resolved.
    *    <br>May or may not be the same object.
    */
   public HeaderInfo resolveRefs(OpenApi openApi, Deque<String> refStack, int maxDepth) {

      if (nn(ref)) {
         if (refStack.contains(ref) || refStack.size() >= maxDepth)
            return this;
         refStack.addLast(ref);
         var r = openApi.findRef(ref, HeaderInfo.class);
         r = r.resolveRefs(openApi, refStack, maxDepth);
         refStack.removeLast();
         return r;
      }
      return this;
   }

   @Override /* Overridden from OpenApiElement */
   public HeaderInfo set(String property, Object value) {
      assertArgNotNull("property", property);
      return switch (property) {
         case "$ref" -> setRef(s(value));
         case "allowEmptyValue" -> setAllowEmptyValue(toBoolean(value));
         case "allowReserved" -> setAllowReserved(toBoolean(value));
         case "deprecated" -> setDeprecated(toBoolean(value));
         case "description" -> setDescription(s(value));
         case "examples" -> setExamples(toMapBuilder(value, String.class, Example.class).sparse().build());
         case "explode" -> setExplode(toBoolean(value));
         case "required" -> setRequired(toBoolean(value));
         case "schema" -> setSchema(toType(value, SchemaInfo.class));
         case "x-example" -> setExample(value);
         default -> {
            super.set(property, value);
            yield this;
         }
      };
   }

   /**
    * Bean property setter:  <property>allowEmptyValue</property>.
    *
    * <p>
    * The type of the object.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setAllowEmptyValue(Boolean value) {
      allowEmptyValue = value;
      return this;
   }

   /**
    * Bean property setter:  <property>allowReserved</property>.
    *
    * <p>
    * The type of the object.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setAllowReserved(Boolean value) {
      allowReserved = value;
      return this;
   }

   /**
    * Bean property setter:  <property>deprecated</property>.
    *
    * <p>
    * The type of the object.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setDeprecated(Boolean value) {
      deprecated = value;
      return this;
   }

   /**
    * Bean property setter:  <property>description</property>.
    *
    * <p>
    * A short description of the header.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setDescription(String value) {
      description = value;
      return this;
   }

   /**
    * Bean property setter:  <property>examples</property>.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   @Beanp("x-example")
   public HeaderInfo setExample(Object value) {
      example = value;
      return this;
   }

   /**
    * Bean property setter:  <property>headers</property>.
    *
    * <p>
    * A list of examples that are sent with the response.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setExamples(Map<String,Example> value) {
      examples.clear();
      if (nn(value))
         examples.putAll(value);
      return this;
   }

   /**
    * Bean property setter:  <property>explode</property>.
    *
    * <p>
    * The type of the object.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setExplode(Boolean value) {
      explode = value;
      return this;
   }

   /**
    * Bean property setter:  <property>$ref</property>.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   @Beanp("$ref")
   public HeaderInfo setRef(String value) {
      ref = value;
      return this;
   }

   /**
    * Bean property setter:  <property>required</property>.
    *
    * <p>
    * The type of the object.
    *
    * @param value
    *    The new value for this property.
    *    <br>Property value is required.
    *    <br>Valid values:
    *    <ul>
    *       <li><js>"string"</js>
    *       <li><js>"number"</js>
    *       <li><js>"integer"</js>
    *       <li><js>"boolean"</js>
    *       <li><js>"array"</js>
    *    </ul>
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setRequired(Boolean value) {
      required = value;
      return this;
   }

   /**
    * Bean property setter:  <property>schema</property>.
    *
    * @param value
    *    The new value for this property.
    *    <br>Can be <jk>null</jk> to unset the property.
    * @return This object
    */
   public HeaderInfo setSchema(SchemaInfo value) {
      schema = value;
      return this;
   }

   @Override /* Overridden from OpenApiElement */
   public HeaderInfo strict(Object value) {
      super.strict(value);
      return this;
   }

   @Override /* Overridden from OpenApiElement */
   protected HeaderInfo strict() {
      super.strict();
      return this;
   }
}